Physical evaluation of four dimensional computed tomography

Mitsuhiro Nakamura, Yuichiro Narita, Yuki Miyabe, Yukinori Matsuo, Takashi Mizowaki, Yoshiki Norihisa, Kenji Takayama, Yasushi Nagata, Masahiro Hiraoka

    Research output: Contribution to journalArticle

    2 Scopus citations


    Purpose: The purpose of this study was to perform physical evaluation of 4D-CT. Materials and Methods: 4D-CT can be accomplished by CT data being correlated, sequentially acquired at each serial couch position, with externally monitored respiratory motion data. The RPM system (Varian Medical Systems, Inc., Palo Alto, CA, USA) recored respiratory motion . A 3D movable phantom system was used to simulate repiratory motion. Phantom studies were performed to measure imaged volume, shape, position and the mean CT number for a moving object. The sphere was automatically segmented using different thresholds on CT images. Results: The volume and the mean CT value correlated highly with the threshold and object motion, while the geometrical center and the sphericity did not show a significant dependency on these parameters. Compared to the standard axial data acquisition, 4D-CT images included only small gross residual motion artifacts. Conclusion: Our study showed that 4D-CT helps reduce artifacts resulting from motion. As a result, more accurate delineation of target, critical structure, and quantifying the extent of the tumor can be achieved. 4D-CT appears to be clinically of great significance in radiotherapy.

    Original languageEnglish (US)
    Pages (from-to)263-271
    Number of pages9
    JournalJournal of JASTRO
    Issue number4
    StatePublished - Dec 1 2007


    • Four-dimensional computed-tomography
    • Physical evaluation respiratory motion

    ASJC Scopus subject areas

    • Radiology Nuclear Medicine and imaging
    • Oncology

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    Nakamura, M., Narita, Y., Miyabe, Y., Matsuo, Y., Mizowaki, T., Norihisa, Y., Takayama, K., Nagata, Y., & Hiraoka, M. (2007). Physical evaluation of four dimensional computed tomography. Journal of JASTRO, 19(4), 263-271.